Viral diseases are often spread either directly via droplet transmission from one human to another human, or indirectly via an animal host that will then transfer the virus in a variety of manners. While numerous virucidal compositions are known in the art, most of them suffer form one or more disadvantage. Most notably, many synthetic compounds tend to be very expensive and often require uptake into a cell to inactivate a virus or stop viral propagation. Furthermore, and especially where synthetic compounds are topically applied, known compounds tend to be chemically aggressive.
Alternatively, natural compounds isolated from one or more plants can be employed as antiviral agents. For example, various anthraquinones and anthraquinone derivatives such as hypericin were demonstrated to be effective against certain viruses, especially in the presence of mild detergents (see e.g., Antiviral Res. 1991 September 16(2):185-96). While such compositions showed significant effect to certain viruses (e.g., vesicular stomatitis virus, herpes simplex type 1 and 2), they were substantially ineffective against other viruses (e.g., human rhinovirus). In other known applications, solid phase articles were impregnated with various plant extracts (e.g., green tea catechins) as described in U.S. Pat. Nos. 5,747,053 and 5,888,527 to Yashimoto et al. Other items (e.g., gargling cup) coated with green tea catechins were described by Hara in GB2300578, and sanitary goods impregnated with organic green tea extracts are taught by Matsutaka in EP 1133999. Once more, while such plant extracts showed significant viral inhibition on various impregnated articles, use of such articles was limited to impregnations. Furthermore, antiviral effect of such formulations is often inconsistent and specificity unpredictable. In still farther known topical applications of plant extracts, including green tea extracts, antibacterial and/or antifungal effect was reported in U.S. Pat. App. No. 2003/0086986. However, these formulations were not reported to have antiviral activity.
Reliable and significant antiviral compositions are especially desirable where the target virus is a rapidly spreading virus. One such example is the SARS coronavirus (SARSCoV), which is an enveloped RNA virus that infects humans. Infected humans typically present a characteristic febrile illness with respiratory symptoms and myalgia, and many patients recover within a few days. However, a significant proportion progress to develop an atypical pneumonia, cumulating in an acute respiratory disease known as Severe Acute Respiratory Syndrome (SARS) with a fatality rate estimated to be about 15%.
SARS emerged as a disease in Southern China in November 2002 but has quickly spread to over 30 countries worldwide. The epidemic has now subsided, but a total of almost 8500 cases with over 800 deaths have been recorded. SARSCoV is transmitted mainly by exposure to respiratory secretions. SARSCoV is most probably derived from a virus that naturally infects a wild or domestic animal. Thus, eradication will be difficult and periodic “re-emergence” from the animal reservoir is possible. For detailed additional information on SARSCoV, reference is made to the “Kamps-Hoffmann SARS reference” (by Flying publisher). Moreover, adaptation of the SARSCoV to humans may result in different patterns, or a higher frequency, of disease and vigilance is therefore advised as there are currently no known safe, non-toxic, and effective virucidal formulations that can be applied to materials, animals, and human.
Thus, while numerous compositions and methods with antiviral activity are known in the art, all or almost all of them suffer from one or more disadvantages. Consequently, there is still a need to provide improved compositions and methods for antiviral compositions, and especially topical antiviral formulations effective against SARSCoV.